1. Technical Field
The present invention relates to semiconductor devices, electronic components, and fabrication processes thereof.
2. Related Art
A semiconductor device that includes external terminal having a resin bump and a wire formed on the resin bump is known (JP-A-2005-101527; Patent Document 1). For example, this type of semiconductor device is mounted as a driving semiconductor device on a glass or plastic wiring substrate of an electronic component such as a liquid crystal display device. Because of the elastic force of the resin bump of the external terminal, such semiconductor device allow the external terminal to be electrically connected to the wiring substrate under applied pressure without causing physical damage, and thus ensure conduction.
It is known that the wiring structure of the external terminal in such semiconductor device is a bilayer structure of a base wiring layer and a surface wiring layer of different metals (Patent Document 1).
The materials of such wiring structures are such that, for example, metallic materials that provide good adhesion for the resin material can be used for the base wiring layer in direct contact with the resin bumps, and that stable metallic materials with good conductivity, and that have corrosion resistance and oxidation resistance can be used for the surface wiring layer.
However, the different metallic materials of the wiring structure have the possibility of causing interdiffusion of the metallic elements at the interface region between the base wiring layer and the surface wiring layer. There is also a possibility that the moisture or oxygen contained in the resin bumps may lower the reliability of the base wiring layer in contact with the resin material.